## Introduction

Welcome to the network Palisade server. The rules of Palisade are below. The Palisade "challenge" command is described here. Other commands are the same for all pbmserv games.

Current games can be viewed here.

palisade challenge [ -size=N ] userid1 userid2
Start a new game between userid1 and userid2.
N = Odd board size. Default board size is 19x19.

(Copyright (c) 2007 Mark Steere <mark@marksteeregames.com>)

AUTHOR'S NOTE: Feel free to distribute this document.

### Introduction

Palisade is played with a Go set. The board starts out empty as shown in Figure 1. The stones shown surrounding the board don’t have to actually be placed there, but the game is played as though they were there.

Each player takes possession of all of the stones of one color. Draws and ties cannot occur in Palisade. Mark Steere designed Palisade in June, 2007.

A B C D E F G

o x o x o x o
7  o . . . . . . . o  7
6  x . . . . . . . x  6
5  o . . . . . . . o  5
4  x . . . . . . . x  4
3  o . . . . . . . o  3
2  x . . . . . . . x  2
1  o . . . . . . . o  1
o x o x o x o

A B C D E F G

Figure 1 -- 7x7 Palisade Board - Initially Empty

### Stone Placement

Players take turns adding their own stones to unoccupied points on the board, one stone per turn.

Points available to X are interspersed with points available to O, in a checkerboard pattern. In Figure 2, the coordinates of the X are (3,1). Note that 3+1 = 4, an even number. The coordinates of the O are (2,3). Note that 2+3 = 5, an odd number. X's can only be placed onto points whose sum of coordinates is even. Likewise for O's and odd sums. In practice it’s not very complicated. You’ll quickly develop an understanding of where stones can be placed and where they can’t. X adds the first stone..

4  . . . . .
3  . . O . .
2  . . . . .
1  . . . X .
0  . . . . .

0 1 2 3 4

Figure 2 -- Coordinates
Sometimes a newly added stone completes the formation of a loop. Here a “loop” is a closed path of like-colored stones. Each stone in the loop is connected to neighboring stones in the loop via diagonal adjacencies.

When you form a loop, if there are any enemy stones within (surrounded by) your loop, then you must remove said enemy stones from the board. Loops are not “protected” in any sense. If you form a loop around an enemy loop, you capture said enemy loop as well as all other enemy stones within your loop.

In Figure 3a, X adds a stone, forming a loop which surrounds two O's. X concludes his turn in Figure 3b by removing the two O's.

. . x . . . .
. x o x o . .
? . . o x o .
o x . x . x o
. o x . x . .
. . o x o . o
x . . o . . .

Figure 3a -- X Initiates Turn (?)

. . x . . . .
. x . x o . .
x . . . x o .
o x . x . x o
. o x . x . .
. . o x o . o
x . . o . . .

Figure 3b -- X Concludes Turn

Sometimes an added stone will form two or more loops simultaneously. In this case, all enemy stones within all of the loops are removed.

The owner of a loop owns all of the points occupied by the loop stones as well as all points within the loop, occupied or unoccupied.

A player must never place a stone within a loop (of either color). Figure 4 shows all of the placements available to X, marked with ?'s. Note the O drawn next to the board. (See Figure 1.)

x o ? o x . x
. ? . ? o x o
x o ? o . o . o
o . o . . . o
x o x o . o x
. x . ? o x .
x . x . x . x

Figure 4 -- Placements Available to X (?)

Each player will always have a placement available, an unobvious property of Palisade. You must make a placement on your turn.

### Object of the Game

When the players own all of the points (occupied and unoccupied), the player who owns the majority of points wins.